IB/core: Add default GIDs of the bond master netdev

Currently following issues exist:
1. Default GIDs of the lower (slave) netdevice if the bond netdevice is
   added. Rather default GID should be of bond master netdevice.
2. Due to this, when failover event occurs FAILOVER event handler attempts
   to delete the GID of the upper device and tries to add the default GID
   of the lower device. This is incorrect behavior.

To have simple and correct code:
(a) Split default GIDs addition out of add_netdev_ips().  This allows
    easier removal in future if RoCE default GIDs are removed.
(b) Add default GIDs of the bond master device by using right filter and
    callback function.
(c) Remove unused function enum_netdev_default_gids().

Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>